Takashi Hibiya

Relationship between the structures and steroidogenic functions of the testes of the urohaze-goby (Glossogobius olivaceus)

The testis of the brackishwater goby (Glossogobius olivaceus, the urohaze-goby in this text) consists of two main components, the glandular and the seminiferous tissue. After manual separation of the two tissues, in vitro steroidogenesis in each tissue was examined using testes from mature males in the breeding season. Cell-free homogenates (800g supernatant fluid) of each tissue were aerobically incubated with 14C-labeled pregnenolone, progesterone, 17 alpha-hydroxyprogesterone, androstenedione, dehydroepiandrosterone, testosterone, or 5 alpha-pregnane-3,20-dione in the presence of NAD+ or NADPH. (1) Glandular tissue: Pregnenolone and dehydroepiandrosterone were converted to progesterone and androstenedione, respectively, in the presence of NAD+. In the presence of NADPH, the following metabolism of steroids was established. Progesterone was transformed to 5 alpha-pregnane-3,20-dione (main product), 17 alpha-hydroxyprogesterone, 17 alpha-hydroxy-5 alpha-pregnane-3,20-dione, and androstenedione. 17 alpha-Hydroxyprogesterone was metabolized into 17 alpha-hydroxy-5 alpha-pregnane-3,20-dione (main product), 3 beta, 17 alpha-dihydroxy-5 alpha-pregnan-20-one, androstenedione, and 5 alpha-androstane-3,17-dione. From androstenedione, 5 alpha-androstane-3,17-dione (main product) and epiandrosterone were obtained. Testosterone was transformed to 5 alpha-dihydrotestosterone (main product), 5 alpha-androstane-3 beta, 17 beta-diol, epiandrosterone, and 5 alpha-androstane-3,17-dione. 5 alpha-Pregnane-3,20-dione was metabolized into 17 alpha-hydroxy-5 alpha-pregnane-3,20-dione, 5 alpha-androstane-3,17-dione, epiandrosterone, and 5 alpha-dihydrotestosterone. (2) Seminiferous tissue: Almost all of the above metabolites were obtained, but the yield was much smaller, especially for 5 alpha-reduced metabolites, compared with that for glandular tissue. From these results, it is concluded that steroidogenesis in the testis of G. olivaceus is characterized by the predominant activity of 5 alpha-reductase and 3 beta-hydroxysteroid dehydrogenase and that these are localized mainly in glandular tissue, together with delta 5-3 beta-hydroxysteroid dehydrogenase + delta 5-delta 4 isomerase, 17 alpha-hydroxylase, and C-17-C-20 lyase.

Structure and steroidogenic enzymes of the seminal vesicles of the urohaze-goby (Glossogobius olivaceus)

The in vitro steroid metabolism in the seminal vesicles of the brackish water goby (urohaze-goby, Glossogobius olivaceus) was studied using males in the breeding season. The moderate activity of delta 5-3 beta-hydroxysteroid dehydrogenase was histochemically detected only in the epithelial cells of the organ, though these cells have the characteristics of secretory cells ultrastructurally. Cell-free homogenates (800 g supernatant fluid) of the whole tissue were aerobically incubated with 14C-labeled pregnenolone, progesterone, 17 alpha-hydroxyprogesterone, androstenedione, dehydroepiandrosterone, or testosterone in the presence of NAD+ or NADPH. Pregnenolone and dehydroepiandrosterone were converted to progesterone and androstenedione, respectively. Progesterone was transformed to 5 alpha-pregnane-3,20-dione (main product) and 17 alpha-hydroxyprogesterone. 17 alpha-Hydroxyprogesterone was metabolized into androstenedione (main product) and 17 alpha-hydroxy-5 alpha-pregnane-3,20-dione. From androstenedione, 5 alpha-androstane-3,17-dione (main product) and epiandrosterone were obtained. Testosterone was transformed to 5 alpha-dihydrotestosterone, 5 alpha-androstane-3 beta, 17 beta-diol, 5 alpha-androstane-3,17-dione, and androstenedione. These results indicate that the steroid metabolic patterns in the seminal vesicles of G. olivaceus are closely resembled to those in the testes.

Minute Tubercles on the Skin Surface of Larvae of Acheilognathus and Pseudoperilampus (Cyprinidae)

It is known that bitterling larvae ofAcheilognathus andPseudoperilampus have minute scalelike tubercles on the skin surface (Uchida, 1937, 1939; Nakamura, 1969). Recently Fukuharaet al. (1982) described minute scaly tubercles distributed on the surface of the yolk sac in the larvae ofAcheilognathus. However, they did not mention the minute tubercles distributed on the skin surface of the whole body and morphological changes of the tubercles with growth of the larvae.The present paper deals with the tubercles distributed on the skin surface of the whole body in the larvae of the following species:Acheilognathus lanceolata, A. limbata, A. tabira tabira, A. tabira subsp. (b),A. moriokae, A. cyanostigma, A. rhombea andPseudoperilampus typus. The skin surface of larvae was divided into three parts (a–c, Fig. 1) to facilitate the description of the distributional patterns of the tubercles. Although the larvae of bothA. lanceolata andA. limbata have minute scale-like tubercles (ca. 20–25 μm in height), which are circular cones that tilt posteriorly on the skin surface of part a of the body, they have numerous hemispheric minute tubercles (ca. 5–10 μm in height) on part b and vestigial minute tubercles on part c. The dorsal part of the yolk sac in both species is slightly developed to form a pair of hilly projections. The larvae ofA. moriokae, A. cyanostigma and subspecies ofA. tabira have minute scale-like tubercles (ca. 20–25 μm in height), which are ellipsoid in diagonal cross section, on the skin surface of both parts a and b of the body and vestigial minute tubercles on part c. The larvae of bothA. rhombea andP. typus have minute scale-like tubercles (ca. 20–40 μm in height) same as thoss in the above-mentioned four species and subspecies on the skin surface of the whole body.The minute scale-like tubercles in all the eight species and subspecies change into hemispheric minute tubercles with growth of the larvae.On the basis of morphological characters of the tubercles, fifteen species and subspecies of acheilognathine fishes were divided into three groups and five types. This classification seems to reflect the phylogenetic relationships among acheilognathine fishes.

Development of the bitterling, Tanakia tanago (Cyprinidae), with a note on minute tubercles on the skin surface.

The development of eggs and larvae and minute tubercles on the skin surface in larvae ofTanakia tanago were observed. The eggs began to hatch approximately 52 hours after insemination and the larvae reached free-swimming stage 19 days after hatching at water temperature of 22±1°C. The egg and larval development and minute tubercles on the skin surface in larvae of this species were similar to those ofAcheilognathus lanceolata andA. limbata. However,T. tanago was distinguishable in egg and larval development fromA. lanceolata andA. limbata by the following characters: the perivitelline space was narrower, embryonic and larval development was faster, and minute tubercles on the skin surface of the anteriormost parts of the yolk sac, and of the body and head were hemispheric in shape. From these characters,T. tanago is considered to be more specialized thanA. lanceolata andA. limbata.